The natural history of hypertension among African-Americans is characterized by a more virulent course, a higher prevalence of target organ damage such as left ventricular hypertrophy (LVH), heart failure and renal failure. It is postulated that this high risk group reflects a hypertensive phenotype in which a predisposition to LVH is associated with abnormalities in endothelial function that predispose to vasoconstriction and structural microvessel occlusion within the coronary circulation. Setting in motion a cascade of pathobiological processes that predispose to myocardial ischemia, recurrent micro-infarctions, heart failure and eventual cardiac mortality. The Specific Aims are: I. Define the relative contribution of ACE/ANGN/EC-NOS genotypes as determinants of brachial artery endothelial dysfunction in African-American hypertensives. II. Define the interrelationship between the ACE/ANGN/EC-NOS genotypes, brachial artery endothelial dysfunction and inducible myocardial ischemia in asymptomatic African-American hypertensives. III. Assess the interrelationship between brachial artery endothelial function, coronary artery endothelial function and inducible myocardial ischemia in symptomatic African-American patients with hypertension. IV. Define the efficacy of chronic treatment with angiotensin converting enzyme inhibitors as a means to improve endothelial function in African-American hypertensives with baseline endothelial dysfunction and inducible myocardial ischemia.